Method and apparatus for measuring state of plurality of channels and for selecting idle channel

ABSTRACT

A method of measuring a state of a plurality of channels is provided. The method includes transmitting to a second device test signal information needed to transmit/receive a test signal for measuring the state of the plurality of channels; receiving an information received response from the second device, indicating that the second device has received the test signal; if the information received response is received, transmitting the test signal to the second device, using the test signal information, via the plurality of channels; and receiving from the second device the state information regarding the plurality of channels which has been measured by using the test signal.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This is a divisional of application Ser. No. 11/937,533 filed Nov. 9,2007, which priority from Korean Patent Application No. 10-2007-0051000,filed on May 25, 2007, in the Korean Intellectual Property Office. Theentire disclosure of the prior applications are considered part of thedisclosure of the accompanying divisional application and are herebyincorporated by reference.

BACKGROUND

1. Technical Field

Methods and apparatuses consistent with the present invention relate tomeasuring a state of a plurality of channels and selecting an idlechannel.

2. Description of the Related Art

A cognitive radio technology determines a current state of a channelaccording to a region and time, and based on the determination, selectsan appropriate frequency, modulation, and an output, so as tocommunicate, dynamically moving an idle channel in real time. Atechnology related to such cognitive radio technology has been activelydeveloped so as to use limited frequency sources.

In order to induct such technology, which efficiently uses the idlechannel, into an ultra high frequency (UHF) band, a technology capableof rapidly detecting a primary user (e.g. a sky wave channel) that has apriority of use of a channel, and capable of communicating betweendevices which are not the primary user, by using the idle channel thatis a channel not used by the primary user, becomes an importanttechnology.

FIG. 1 is a diagram illustrating a conventional method of scanning achannel state.

In operation 110, a base station transmits to a terminal a channel statescanning request for scanning the channel state.

In operation 120, the terminal transmits to the base station a requestreceived response indicating that the terminal has received the channelstate scanning request.

At this time, if the base station does not receive the request receivedresponse, the base station again transmits the channel state scanningrequest to the terminal.

In operation 130, the terminal reports to the base station the channelstate scanned according to the channel state scanning request.

In operation 140, the base station transmits to the terminal a reportreceived response indicating that the base station has received thechannel state report from the terminal.

At this time, if the terminal does not receive the report receivedresponse, the terminal again reports the channel state to the basestation.

Here, the base station receives the report including informationregarding communication quality of the channel, and whether the channelis in use.

However, the conventional method has problems in that the conventionalmethod does not provide a specific method of measuring communicationquality of a plurality of channels, and when the base station and theterminal select an idle channel from among a plurality of idle channelsso as to perform communication, the conventional method does notconsider a location of a terminal, an application, or the like.

SUMMARY

Aspects of the present invention provide a method and apparatus formeasuring a state of a plurality of channels which measure communicationquality of the plurality of channels.

Aspects of the present invention also provide a method and apparatus forselecting an idle channel from among a plurality of idle channels bywhich a base station and a terminal can perform communicationefficiently.

According to an aspect of the present invention, there is provided amethod of measuring a state of a plurality of channels capable of beingused in communication between a first device and a second device, themethod including: transmitting test signal information that isinformation needed to transmit and receive a test signal for measuringthe state of the plurality of channels, to the second device; receivingan information received response from the second device, indicating thatthe second device has received the test signal information; transmittingthe test signal based on the test signal information to the seconddevice via the plurality of channels, if the information receivedresponse is received; and receiving state information regarding theplurality of channels, which has been measured by using the test signal,from the second device.

The method of measuring the state of the plurality of channels capableof being used in the communication between the first device and thesecond device may include the operation of scanning idle channels fromamong all channels, wherein the plurality of channels may be the scannedidle channels.

The method of measuring the state of the plurality of channels capableof being used in the communication between the first device and thesecond device may further include the operations of transmitting achannel state measurement start request for starting to measure thestate of the plurality of channels, to the second device; and receivingthe start request received response indicating that the channel statemeasurement start request is received. If the start request receivedresponse is received, the operation of transmitting the test signal maytransmit the test signal information to the second device.

The test signal information may include a test signal transmissionperiod that is the time required after a predetermined channel hastransmitted the test signal until another channel again transmits thetest signal, a start channel number that is the channel to be used toinitially transmit the test signal, and an end channel number that isthe channel to be used to finally transmit the test signal.

The state information regarding the plurality of channels is generatedby calculating a signal-to-noise ratio from the test signals which havebeen received via the respective channels of the plurality of channels.

The state information regarding the plurality of channels comprisesvalues obtained by denoting, numerically, respective communicationqualities of the plurality of channels, and by then normalizing valuesof the respective communication qualities that have been denotednumerically.

According to another aspect of the present invention, there is provideda method of selecting an idle channel from among a plurality of idlechannels for communication between a first device and a plurality ofsecond devices, the method comprising: setting a priority for respectiveidle channels from among the plurality of idle channels, using at leastone of distance information regarding a distance between the firstdevice and the respective second devices, preference information for anidle channel of the respective second devices and applicationinformation regarding an application provided by the respective seconddevices; and selecting the idle channel for communication with theplurality of second devices using the set priority.

The operation of setting the priority may set the priority based on adatabase storing at least one of the distance information regarding thedistance between the first device and the second device, the preferenceinformation for the idle channel of the second device, and theapplication information regarding the application provided by the seconddevice.

The operation of setting the priority may set one of the respective idlechannels to have a high priority, if the one of the respective idlechannels is preferred by the second device that provides a moreimportant application from among the plurality of second devices and thethird device.

The operation of setting the priority may set one of the respective idlechannels to have a high priority, if the one of the respective idlechannels is preferred by the second device that is located farthest fromthe first device from among the plurality of second devices. Preferenceinformation regarding the idle channel of the second device isinformation generated based on a priority for the plurality of idlechannels, wherein the priority is generated according to communicationquality measured for the respective idle channels of the plurality ofchannels by the second device.

According to another aspect of the present invention, there is providedan apparatus for measuring a state of a plurality of channels capable ofbeing used in a communication between a first device and a seconddevice, the apparatus including: a transmission unit transmitting testsignal information that is information needed to transmit and receive atest signal for measuring the state of the plurality of channels, to thesecond device; and a reception unit receiving an information receivedresponse from the second device, indicating that the second device hasreceived the test signal information. The transmission unit transmitsthe test signal based on the test signal information to the seconddevice via the plurality of channels, if the information receivedresponse is received; and the reception unit receives state informationfor the plurality of channels which has been measured by using the testsignal, from the second device.

The apparatus for measuring the state of the plurality of channelscapable of being used in the communication between the first device andthe second device may further include an idle channel scan unit scanningidle channels from among all channels, wherein the plurality of channelsare the idle channels scanned by the idle channel scan unit.

According to another aspect of the present invention, there is providedan apparatus for selecting an idle channel from among a plurality ofidle channels for communication between a first device and a pluralityof second devices, the apparatus comprising: a priority set unit whichsets a priority for respective idle channels from among the plurality ofidle channels, using at least one of distance information regarding adistance between the first device and the respective second devices,preference information for an idle channel of the respective seconddevices and application information regarding an application provided bythe respective second devices; and a channel selection unit whichselects the idle channel for communication with the plurality of seconddevices using the set priority. According to another aspect of thepresent invention, there is provided a computer readable recordingmedium storing a computer readable program for executing a method ofmeasuring a state of a plurality of channels capable of being used incommunication between a first device and a second device, the methodincluding: transmitting test signal information that is informationneeded to transmit and receive a test signal for measuring the state ofthe plurality of channels, to the second device; receiving aninformation received response from the second device, indicating thatthe second device has received the test signal information; transmittingthe test signal based on the test signal information to the seconddevice via the plurality of channels, if the information receivedresponse is received; and receiving state information on the pluralityof channels, which has been measured by using the test signal, from thesecond device.

According to another aspect of the present invention, there is provideda computer readable recording medium storing a computer readable programfor executing a method of selecting an idle channel from among aplurality of idle channels for communication between a first device anda plurality of second devices, the method comprising: setting a priorityfor respective idle channels from among the plurality of idle channels,using at least one of distance information regarding a distance betweenthe first device and the respective second devices, preferenceinformation for an idle channel of the respective second devices andapplication information regarding an application provided by therespective second devices; and selecting the idle channel forcommunication with the plurality of second devices using the setpriority.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will become moreapparent by describing in detail exemplary embodiments thereof withreference to the attached drawings, in which:

FIG. 1 is a diagram illustrating a conventional method of scanning achannel state;

FIG. 2 is a diagram illustrating a method of measuring a state of aplurality of channels according to an exemplary embodiment of thepresent invention;

FIG. 3 is a block diagram of an apparatus for measuring a state of aplurality of channels according to another exemplary embodiment of thepresent invention;

FIG. 4 is a diagram illustrating state information regarding channelsaccording to another exemplary embodiment of the present invention;

FIG. 5 is a diagram illustrating preference information regardingchannels according to another exemplary embodiment of the presentinvention;

FIG. 6 is a block diagram of an idle channel selection apparatusaccording to another exemplary embodiment of the present invention; and

FIG. 7 is a block diagram of a method of setting the priority for theidle channel according to another exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

The present invention will now be described more fully with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown.

FIG. 2 is a diagram illustrating a method of measuring a state of aplurality of channels according to an exemplary embodiment of thepresent invention.

In operation 210, a first device transmits test signal information thatis information needed to transmit/receive a test signal for measuringthe state of the plurality of channels, to a second device.

According to the exemplary embodiment of FIG. 2, the test signalinformation may include a test signal transmission period that is thetime required after a predetermined channel has transmitted the testsignal until another channel again transmits the test signal, a startchannel number that is the channel to be used to initially transmit thetest signal, and an end channel number that is the channel to be used tofinally transmit the test signal.

However, according to other exemplary embodiments, operation 210 mayfurther include the operation of transmitting in which the first devicetransmits a channel state measurement start request to the second devicerequiring starting to measure a state of a plurality of channels and theoperation of receiving in which the first device receives a startrequest received response indicating that the second device has receivedthe channel state measurement start request.

According to the exemplary embodiment of FIG. 2, the plurality ofchannels may be a plurality of idle channels, and in this case,operation 210 may further include the operation of scanning the idlechannels from among all channels.

That is, exemplary embodiments of the present invention may not onlymeasure a channel state of a plurality of channels determined by a userbut also a channel state of idle channels.

Further, the first device may be a base station or a set-top box, andthe second device may be a terminal. According to the exemplaryembodiment of FIG. 2, the terminal denotes all devices capable ofcommunicating with the first device, such as a digital television (DTV),a portable multimedia player (PMP), an MPEG Audio Layer-3 (MP3) player,a notebook, a mobile phone, or the like.

In operation 220, the first device receives an information receivedresponse from the second device, indicating that the second device hasreceived the test signal information.

In operation 230, if the information received response is received, thefirst device transmits the test signal based on the test signalinformation to the second device via the plurality of channels.

According to the exemplary embodiment of FIG. 2, if the informationreceived response is not received, the first device does not transmitthe test signal but instead transmits the test signal information to thesecond device again.

In operation 240, the first device receives state information regardingthe plurality of channels, which has been measured by using the testsignal, from the second device.

According to the exemplary embodiment of FIG. 2, the state informationregarding the plurality of channels may be generated by calculating asignal-to-noise ratio from the test signals which the second device hasreceived via the respective channels of the plurality of channels.

Also, the state information on the plurality of channels may be formedof values obtained by denoting numerically respective communicationqualities of the plurality of channels, and by then normalizing valuesof the respective communication qualities that have been denotednumerically.

FIG. 3 is a block diagram of an apparatus for measuring a state of aplurality of channels according to another exemplary embodiment of thepresent invention.

Referring to FIG. 3, a first device 310 that is the apparatus formeasuring the state of the plurality of channels includes a transmissionunit 312, and a reception unit 314.

The transmission unit 312 transmits test signal information that isinformation needed to transmit/receive a test signal for measuring thestate of the plurality of channels, to a second device 320.

The reception unit 314 receives an information received response fromthe second device 320, indicating that the second device 320 hasreceived the test signal information.

In this way, when the information received response is received by thereception unit 314, the transmission unit 312 transmits the test signalbased on the test signal information to the second device 320 via theplurality of channels.

Finally, the reception unit 314 receives state information regarding theplurality of channels which has been measured by using the test signal,from the second device 320.

FIG. 4 is a diagram illustrating state information regarding channelsaccording to another exemplary embodiment of the present invention.

FIG. 4 is a diagram showing the results when a terminal ‘1’, a terminal‘2’, and a terminal ‘3’ have measured communication qualities of idlechannels ‘23’, ‘29’, ‘37’, and ‘41’.

Referring to FIG. 4, the communication qualities of the respectivechannels are denoted by using a value in the range of 1 through 10. Theworst communication quality is denoted as 1, and the best communicationquality is denoted as 10.

Meanwhile, according to a good/bad quality of the measured communicationquality, preferred channel information for the respective terminals maybe obtained.

FIG. 5 is a diagram illustrating preference information regardingchannels according to another exemplary embodiment of the presentinvention.

Referring to FIG. 5, a list of channels preferred by respectiveterminals 1 through 3 is shown in order of preference of the terminals.

For example, terminal ‘1’ prefers a channel ‘41’ the most, and seldomprefers channel ‘37’.

The preference for the channels is generated based on the communicationqualities that have been measured for the respective channels from amongthe plurality of channels by the respective terminals, as shown in FIG.3.

An exemplary method of measuring the state of the plurality of channelsis described above.

An exemplary method of selecting a channel from among a plurality ofidle channels, by using the preference information for the channels willnow be described.

FIG. 6 is a block diagram of an idle channel selection apparatusaccording to another exemplary embodiment of the present invention.

Referring to FIG. 6, the idle channel selection apparatus includes apriority set unit 610, and a channel selection unit 620.

The priority set unit 610 sets the priority for the respective idlechannels of the plurality of idle channels, based on at least one ofdistance information regarding the distance between the idle channelselection apparatus and a terminal, preference information regarding anidle channel of the terminal, and application information regarding theapplication provided by the terminal.

According to the exemplary embodiment shown in FIG. 6, the terminaldenotes all devices capable of communicating with the idle channelselection apparatus, such as a DTV, a PMP, an MP3 player, a notebook, amobile phone, or the like.

Also, the priority set unit 610 may set the priority for the respectiveidle channels of the plurality of idle channels, based on a databasestoring the distance information regarding the distance between the idlechannel selection apparatus and the terminal, the preference informationregarding the idle channel of the terminal, and the applicationinformation regarding the application provided by the terminal.

The operation of the priority set unit 610 will be described morespecifically in relation to FIG. 7.

Based on the priority set in the priority set unit 610, the channelselection unit 620 selects the idle channel from among the plurality ofidle channels. The selected idle channel is to be used in communicationwith the terminal.

That is, according to results set in the priority set unit 610, thechannel selection unit 620 selects the idle channel having a toppriority, as the idle channel to be used in the communication with theterminal.

However, when the idle channel having the top priority cannot be used,the channel selection unit 620 selects the idle channel having a secondtop priority.

A method of setting a priority for an idle channel will now be describedin relation to FIG. 7.

FIG. 7 is a block diagram of the method of setting the priority for theidle channel according to another exemplary embodiment of the presentinvention.

In FIG. 7, an idle channel selection apparatus 700, and terminals 710,720, and 730 for performing communication with the idle channelselection apparatus 700, are illustrated.

According to the exemplary embodiment shown in FIG. 7, the terminals710, 720, and 730 are located away from the idle channel selectionapparatus 700 at predetermined distances. The terminal ‘1’ 710, theterminal ‘2’ 720, and the terminal ‘3’ 730 are respectively 5 meters, 10meters, and 7 meters away from the idle channel selection apparatus 700.

In the case of the plural terminals shown in FIG. 7, when the idlechannel selection apparatus 700 selects the idle channel that is to beused in the communication with the terminals 710, 720, and 730, the idlechannel selection apparatus 700 considers primarily the idle channelswhich are preferred by the terminal located farthest from the idlechannel selection apparatus 700, from among the plurality of terminals710, 720, and 730.

For example, the terminal ‘2’ 720 is located farthest from the idlechannel selection apparatus 700 as shown in FIG. 7. Thus, the idlechannel selection apparatus 700 primarily considers a preference for theidle channel of the terminal ‘2’ 720 over a preference for the idlechannels of the terminals 710, and 730.

That is, according to the preference for the idle channel of theterminal ‘2’ 720, the idle channel selection apparatus 700 determines apriority of the idle channels that are to be used in the communicationwith the terminals 710, 720, and 730.

Referring to FIG. 5, the priority for the idle channels of the terminal‘2’ 720 is determined sequentially from a channel ‘29’, a channel ‘23’,a channel ‘37’, and a channel ‘41’. Hence, in the aforementionedexample, the idle channel selection apparatus 700 determines thepriority of the idle channels sequentially from channel ‘29’, channel‘23’, channel ‘37’, and channel ‘41’.

Moreover, the respective terminals 710, 720, and 730 may providerespectively different kinds of applications.

In the case of the plural terminals shown in FIG. 7, when the idlechannel selection apparatus 700 selects the idle channel that is to beused in the communication with the terminals 710, 720, and 730, the idlechannel selection apparatus 700 primarily considers idle channelspreferred by the terminal which provides a more important application,from among the plurality of terminals 710, 720, and 730.

In the case where the respective terminals 710, 720, and 730 providedifferent kinds of applications, the idle channels preferred by theterminal which provides the more important application among theterminals 710, 720, and 730, are set to have a high priority.

For example, the terminal ‘1’ 710, the terminal ‘2’ 720, and theterminal ‘3’ 730 may be, respectively, a high definition television(HDTV), a standard definition television (SDTV), and an audio player.

In this case, a priority of the application may be determinedsequentially from the HDTV, the SDTV, and the audio player. In the casewhere the priority of the application is determined in this manner, theidle channel selection apparatus 700 determines a priority of the idlechannels that are to be used between the idle channel selectionapparatus 700 and the terminals 710, 720, and 730, according to apreference for the idle channel of the terminal ‘1’ 710.

Referring to FIG. 5, the priority of the idle channels preferred by theterminal ‘1’ 710 is set sequentially from a channel ‘41’, a channel‘29’, a channel ‘23’, and a channel ‘37’. Thus, in the above example,the idle channel selection apparatus 700 determines the priority of theidle channels sequentially from channel ‘41’, channel ‘29’, channel‘23’, and channel ‘37’.

Also, in determining the priority of the idle channel, informationregarding an application provided by a terminal is considered to be moreprimary than information regarding a distance between terminals.

For example, in FIG. 7, since the terminal ‘2’ 720 is located fartherfrom the idle channel selection apparatus 700 than the terminal ‘1’ 710,basically, the idle channel selection apparatus 700 has to determine thepriority of the idle channel that is to be used in the communicationwith a terminal, according to the preference for the idle channel of theterminal ‘2’ 720. However, in the case where the terminal ‘1’ 710provides a more important application than the terminal ‘2’ 720, theidle channel selection apparatus 700 determines the priority of the idlechannel that is to be used in the communication with the terminals,according to the preference for the idle channel of the terminal ‘1’710.

Exemplary embodiments of the present invention can transmit the testsignal information needed to transmit/receive the test signal formeasuring the state of the plurality of channels, to the second device,and receive the information received response from the second device,indicating that the second device has received the test signal. If theinformation received response is received, exemplary embodiments of thepresent invention can transmit the test signal based on the test signalinformation to the second device via the plurality of channels, andreceive the state information regarding the plurality of channels whichhas been measured by using the test signal, from the second device.Accordingly, the communication quality of the plurality of channels canbe measured.

Also, exemplary embodiments of the present invention can select the idlechannel from among the plurality of idle channels, by which a basestation and terminal effectively perform communication.

The exemplary embodiments of the present invention can be written ascomputer programs and can be implemented in general-use digitalcomputers that execute the programs using a computer readable recordingmedium. Examples of such a computer readable recording medium include,but are not limited to, magnetic storage media (e.g., ROM, floppy disks,hard disks, etc.), optical recording media (e.g., CD-ROMs, or DVDs), andstorage media such as carrier waves (e.g., transmission through theInternet).

While this invention has been particularly shown and described withreference to exemplary embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the invention as defined by the appended claims. The exemplaryembodiments should be considered in a descriptive sense only and not forpurposes of limitation. Therefore, the scope of the invention is definednot by the detailed description of the exemplary embodiments ofinvention but by the appended claims, and all differences within thescope will be construed as being included in the present invention.

1. A method of selecting an idle channel from among a plurality of idlechannels for communication between a first device and a plurality ofsecond devices, the method comprising: setting a priority for respectiveidle channels from among the plurality of idle channels, using at leastone of: distance information regarding a distance between the firstdevice and the respective second devices; preference information for anidle channel of the respective second devices; and applicationinformation regarding an application provided by the respective seconddevices; and selecting the idle channel for communication with theplurality of second devices using the set priority.
 2. The method ofclaim 1, wherein the setting of the priority comprises: setting thepriority using a database storing at least one of: the distanceinformation regarding the distance between the first device and thesecond device, the preference information for the idle channel of thesecond device, and the application information regarding the applicationprovided by the second device.
 3. The method of claim 1, wherein thesetting of the priority comprises setting one of the respective idlechannels to have a high priority, if the one of the respective idlechannels is preferred by the second device that provides a moreimportant application from among the plurality of second devices and thethird device.
 4. The method of claim 1, wherein the setting of thepriority comprises setting one of the respective idle channels to have ahigh priority, if the one of the respective idle channels is preferredby the second device that is located farthest from the first device fromamong the plurality of second devices.
 5. The method of claim 1, whereinpreference information regarding a preferred idle channel of the seconddevice comprises information generated using a priority for each of theplurality of idle channels, wherein the priority for each of theplurality of idle channels is generated according to communicationquality measured for the respective idle channel by the second device.6. A computer readable recording medium having recorded thereon aprogram for executing the method of claim
 1. 7. An apparatus forselecting an idle channel from among a plurality of idle channels forcommunication between a first device and a plurality of second devices,the apparatus comprising: a priority set unit which sets a priority forrespective idle channels from among the plurality of idle channels,using at least one of: distance information regarding a distance betweenthe first device and the respective second devices; preferenceinformation for an idle channel of the respective second devices; andapplication information regarding an application provided by therespective second devices; and a channel selection unit which selectsthe idle channel for communication with the plurality of second devicesusing the set priority.
 8. The apparatus of claim 7, wherein thepriority set unit sets the priority using a database storing at leastone of: the distance information regarding the distance between thefirst device and the second device, the preference information for theidle channel of the second device, and the application informationregarding the application provided by the second device.
 9. Theapparatus of claim 7, wherein the priority set unit sets one of therespective idle channels to have a high priority, if the one of therespective idle channels is preferred by one of the second device andthe third device that provides a more important application from amongthe plurality of second devices and the third device.
 10. The apparatusof claim 7, wherein the priority set unit sets one of the respectiveidle channels to have a high priority, if the one of the respective idlechannels is preferred by one of the second device and the third devicethat is located farthest from the first device from among the pluralityof second devices and the third device.
 11. The apparatus of claim 7,wherein preference information regarding a preferred idle channel of thesecond device comprises information generated using a priority for eachof the plurality of idle channels, wherein the priority for each of theplurality of idle channels is generated according to communicationquality measured for the respective idle channel by the second device.